Method for receiving or transmitting reference signal for location determination in wireless communication system and device for same

ABSTRACT

A method for measuring a reference signal for location determination in a wireless communication system, according to an embodiment of the present invention, is performed by means of a terminal. The method comprises the steps of: receiving assistant data related to neighbor cells and a reference cell for location determination; by means of the assistant data, receiving a positioning reference signal (PRS) of a cell-specific reference signal (CRS) of the reference cell or the neighbor cells and calculating a reference signal time difference (RSTD) measurement value; and reporting the measurement value to a location server, wherein the assistant data can comprise information about the number of CRS antenna ports of the reference cell and neighbor cells, CRS cyclic prefix (CP) length information, or configuration information about multicast broadcast single frequency network (MBSFN) subframes.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method of measuring a reference signal fordetermining a location or a method of determining a location in awireless communication system and an apparatus therefor.

BACKGROUND ART

Recently, various devices requiring machine-to-machine (M2M)communication and high data transfer rate, such as smartphones or tabletpersonal computers (PCs), have appeared and come into widespread use.This has rapidly increased the quantity of data which needs to beprocessed in a cellular network. In order to satisfy such rapidlyincreasing data throughput, recently, carrier aggregation (CA)technology which efficiently uses more frequency bands, cognitive ratiotechnology, multiple antenna (MIMO) technology for increasing datacapacity in a restricted frequency, multiple-base-station cooperativetechnology, etc. have been highlighted. In addition, communicationenvironments have evolved such that the density of accessible nodes isincreased in the vicinity of a user equipment (UE). Here, the nodeincludes one or more antennas and refers to a fixed point capable oftransmitting/receiving radio frequency (RF) signals to/from the userequipment (UE). A communication system including high-density nodes mayprovide a communication service of higher performance to the UE bycooperation between nodes.

A multi-node coordinated communication scheme in which a plurality ofnodes communicates with a user equipment (UE) using the sametime-frequency resources has much higher data throughput than legacycommunication scheme in which each node operates as an independent basestation (BS) to communicate with the UE without cooperation.

A multi-node system performs coordinated communication using a pluralityof nodes, each of which operates as a base station or an access point,an antenna, an antenna group, a remote radio head (RRH), and a remoteradio unit (RRU). Unlike the conventional centralized antenna system inwhich antennas are concentrated at a base station (BS), nodes are spacedapart from each other by a predetermined distance or more in themulti-node system. The nodes can be managed by one or more base stationsor base station controllers which control operations of the nodes orschedule data transmitted/received through the nodes. Each node isconnected to a base station or a base station controller which managesthe node through a cable or a dedicated line.

The multi-node system can be considered as a kind of Multiple InputMultiple Output (MIMO) system since dispersed nodes can communicate witha single UE or multiple UEs by simultaneously transmitting/receivingdifferent data streams. However, since the multi-node system transmitssignals using the dispersed nodes, a transmission area covered by eachantenna is reduced compared to antennas included in the conventionalcentralized antenna system. Accordingly, transmit power required foreach antenna to transmit a signal in the multi-node system can bereduced compared to the conventional centralized antenna system usingMIMO. In addition, a transmission distance between an antenna and a UEis reduced to decrease in pathloss and enable rapid data transmission inthe multi-node system. This can improve transmission capacity and powerefficiency of a cellular system and meet communication performancehaving relatively uniform quality regardless of UE locations in a cell.Further, the multi-node system reduces signal loss generated duringtransmission since base station(s) or base station controller(s)connected to a plurality of nodes transmit/receive data in cooperationwith each other. When nodes spaced apart by over a predetermineddistance perform coordinated communication with a UE, correlation andinterference between antennas are reduced. Therefore, a high signal tointerference-plus-noise ratio (SINR) can be obtained according to themulti-node coordinated communication scheme.

Owing to the above-mentioned advantages of the multi-node system, themulti-node system is used with or replaces the conventional centralizedantenna system to become a new foundation of cellular communication inorder to reduce base station cost and backhaul network maintenance costwhile extending service coverage and improving channel capacity and SINRin next-generation mobile communication systems.

DISCLOSURE OF THE INVENTION Technical Task

A technical task of the present invention is to propose a method ofdetermining a location based on a reference signal.

Technical tasks obtainable from the present invention are non-limitedthe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

Technical Solution

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, accordingto one embodiment, a method of measuring a reference signal forpositioning in a wireless communication system, the method performed bya terminal and includes receiving assistant data related to a referencecell and one or more neighbor cells for positioning, calculating areference signal time difference (RSTD) measurement value by receiving apositioning reference signal (PRS) or a cell-specific reference signal(CRS) of the reference cell and the one or more neighbor cells using theassistant data, and reporting the measurement value to a locationserver. In this case, the assistant data may include information on thenumber of CRS antenna ports, CRS cyclic prefix (CP) length information,and configuration information on multicast broadcast single frequencynetwork (MBSFN) subframes of the reference cell and the one or moreneighbor cells.

Additionally or alternatively, the information on the number of CRSantenna ports can indicate one selected from the group consisting of 1,2, and 4.

Additionally or alternatively, the CRS CP length information may existonly when a CP length of a PRS of the reference cell is different from aCP length of a CRS of the reference cell or a CP length of a PRS of theone or more neighbor cells is different from a CP length of a CRS of theone or more neighbor cells.

Additionally or alternatively, if the CRS CP length information is notincluded in the assistant data, the CP length of the PRS of thereference cell may be identical to the CP length of the CRS of thereference cell or the CP length of the PRS of the one or more neighborcells may be identical to the CP length of the CRS of the one or moreneighbor cells.

Additionally or alternatively, the configuration information on theMBSFN subframes may be provided in a unit of 1 or 4 radio frames.

Additionally or alternatively, when the assistant data related to aspecific cell of the one or more neighbor cells does not include all ora part of the information on the number of CRS antenna ports, the CRS CPlength information, and the configuration information on the MBSFNsubframes, a CRS may not be used for measuring the RSTD measurement forthe specific cell.

Additionally or alternatively, when the assistant data related to aspecific cell of the one or more neighbor cells does not include all ora part of the information on the number of CRS antenna ports, the CRS CPlength information, and the configuration information on the MBSFNsubframes, the method may further include calculating the RSTDmeasurement value by receiving a CRS only transmitted via a CRS port 0of the specific cell.

Additionally or alternatively, if the assistant data related to aspecific cell of the one or more neighbor cells does not include all ora part of the information on the number of CRS antenna ports, the CRS CPlength information, and the configuration information on the MBSFNsubframes, the method may further include calculating the RSTDmeasurement value by receiving a CRS on a specific OFDM symbol only,which transmitted from the specific cell.

Additionally or alternatively, if the assistant data related to aspecific cell of the one or more neighbor cells does not include all ora part of the information on the number of CRS antenna ports, the CRS CPlength information, and the configuration information on the MBSFNsubframes, the method may further include calculating the RSTDmeasurement value by receiving a PRS only, which transmitted from thespecific cell.

Additionally or alternatively, if a physical layer cell identifier (ID)field of the reference cell is identical to a physical cell ID of atleast one neighbor cell among the one or more neighbor cells, only a PRSof the reference cell may be used for measuring RSTD and RSTDmeasurement may not be performed for the at least one neighbor cell.

Additionally or alternatively, if a physical layer cell identifier (ID)field of the reference cell is identical to a physical cell ID of atleast one neighbor cell among the one or more neighbor cells, only a PRSof the reference cell may be used for measuring RSTD and only a PRS ofthe at least one neighbor cell may be used for measuring RSTD.

Additionally or alternatively, if a physical layer cell identifier (ID)field of the reference cell is identical to a physical cell ID of atleast one neighbor cell among the one or more neighbor cells, a PRSand/or a CRS of the reference cell may be used for measuring RSTD andRSTD measurement may not be performed on the at least one neighbor cell.

Additionally or alternatively, if a physical layer cell identifier (ID)field of the reference cell is identical to a physical cell ID of atleast one neighbor cell among the one or more neighbor cells, a PRSand/or a CRS of the reference cell may be used for measuring RSTD andonly a PRS of the at least one neighbor cell may be used for measuringRSTD.

Additionally or alternatively, if physical layer cell identifiers (IDs)of a plurality of neighbor cells included in the assistant data areidentical to each other, only a PRS of a predetermined neighbor cellamong the plurality of the neighbor cells is used for measuring RSTD andRSTD measurement may not be performed on the remaining neighbor cellsother than the predetermined neighbor cell.

Additionally or alternatively, if physical layer cell identifiers (IDs)of a plurality of neighbor cells included in the assistant data areidentical to each other, only a PRS of a predetermined neighbor cellamong the plurality of the neighbor cells is used for measuring RSTD andonly PRS of the remaining neighbor cells other than the predeterminedneighbor cell may be used for measuring RSTD.

Additionally or alternatively, if physical layer cell identifiers (IDs)of a plurality of neighbor cells included in the assistant data areidentical to each other, a PRS and/or a CRS of a predetermined neighborcell among a plurality of the neighbor cells is used for measuring RSTDand RSTD measurement may not be performed on the remaining neighborcells.

Additionally or alternatively, if physical layer cell identifiers (IDs)of a plurality of neighbor cells included in the assistant data areidentical to each other, a PRS and/or a CRS of a predetermined neighborcell among the plurality of the neighbor cells may be used for measuringRSTD and only PRSs of the remaining neighbor cells other than thepredetermined neighbor cell may be used for measuring RSTD.

Additionally or alternatively, the method may further include receivinginformation on a specific reference signal (RS), which is in aquasi-co-location (QCL) relation with the PRS of the reference cell orthe one or more neighbor cells. In this case, the information on thespecific RS may be used for determining a channel property of the PRS,which is in the QCL relation with the RS.

Additionally or alternatively, the information on the specific RS mayinclude information on a specific antenna port of the RS, which is inthe QCL relation with the PRS.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a different embodiment, auser equipment configured to measure a reference signal for positioningin a wireless communication system includes a transmitter, a receiver,and a processor that controls the transmitter and the receiver, whereinthe processor controls the receiver to receive assistant data related toa reference cell and one or more neighbor cells for positioning,calculates an reference signal time difference (RSTD) measurement valueby receiving a positioning reference signal (PRS) or a cell-specificreference signal (CRS) of the reference cell and the one or moreneighbor cells using the assistant data, and reports the measurementvalue to a location server. In this case, the assistant data may includeinformation on the number of CRS antenna ports, CRS cyclic prefix (CP)length information, and configuration information on multicast broadcastsingle frequency network (MBSFN) subframes of the reference cell and theone or more neighbor cells.

Technical solutions obtainable from the present invention arenon-limited the above-mentioned technical solutions. And, otherunmentioned technical solutions can be clearly understood from thefollowing description by those having ordinary skill in the technicalfield to which the present invention pertains.

Advantageous Effects

According to one embodiment of the present invention, it is able toefficiently receive or transmit a reference signal for determining alocation and measure the reference signal in a wireless communicationsystem.

Effects obtainable from the present invention may be non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a diagram for an example of a radio frame structure used in awireless communication system;

FIG. 2 is a diagram for an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system;

FIG. 3 is a diagram for an example of a downlink (DL) subframe structureused in 3GPP LTE/LTE-A system;

FIG. 4 is a diagram for an example of an uplink (UL) subframe structureused in 3GPP LTE/LTE-A system;

FIG. 5 is a diagram for a PRS transmission structure;

FIGS. 6 and 7 are diagrams for RE mapping of a PRS (positioningreference signal);

FIG. 8 is a diagram illustrating an operation according to oneembodiment of the present invention;

FIG. 9 is a block diagram of a device for implementing embodiment(s) ofthe present invention.

BEST MODE Mode for Invention

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The accompanying drawings illustrate exemplary embodiments ofthe present invention and provide a more detailed description of thepresent invention. However, the scope of the present invention shouldnot be limited thereto.

In some cases, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

In the present invention, a user equipment (UE) is fixed or mobile. TheUE is a device that transmits and receives user data and/or controlinformation by communicating with a base station (BS). The term ‘UE’ maybe replaced with ‘terminal equipment’, ‘Mobile Station (MS)’, ‘MobileTerminal (MT)’, ‘User Terminal (UT)’, ‘Subscriber Station (SS)’,‘wireless device’, ‘Personal Digital Assistant (PDA)’, ‘wireless modem’,‘handheld device’, etc. A BS is typically a fixed station thatcommunicates with a UE and/or another BS. The BS exchanges data andcontrol information with a UE and another BS. The term ‘BS’ may bereplaced with ‘Advanced Base Station (ABS)’, ‘Node B’, ‘evolved-Node B(eNB)’, ‘Base Transceiver System (BTS)’, ‘Access Point (AP)’,‘Processing Server (PS)’, etc. In the following description, BS iscommonly called eNB.

In the present invention, a node refers to a fixed point capable oftransmitting/receiving a radio signal to/from a UE by communication withthe UE. Various eNBs can be used as nodes. For example, a node can be aBS, NB, eNB, pico-cell eNB (PeNB), home eNB (HeNB), relay, repeater,etc. Furthermore, a node may not be an eNB. For example, a node can be aradio remote head (RRH) or a radio remote unit (RRU). The RRH and RRUhave power levels lower than that of the eNB. Since the RRH or RRU(referred to as RRH/RRU hereinafter) is connected to an eNB through adedicated line such as an optical cable in general, cooperativecommunication according to RRH/RRU and eNB can be smoothly performedcompared to cooperative communication according to eNBs connectedthrough a wireless link. At least one antenna is installed per node. Anantenna may refer to an antenna port, a virtual antenna or an antennagroup. A node may also be called a point. Unlike a conventionalcentralized antenna system (CAS) (i.e. single node system) in whichantennas are concentrated in an eNB and controlled an eNB controller,plural nodes are spaced apart at a predetermined distance or longer in amulti-node system. The plural nodes can be managed by one or more eNBsor eNB controllers that control operations of the nodes or schedule datato be transmitted/received through the nodes. Each node may be connectedto an eNB or eNB controller managing the corresponding node via a cableor a dedicated line. In the multi-node system, the same cell identity(ID) or different cell IDs may be used for signal transmission/receptionthrough plural nodes. When plural nodes have the same cell ID, each ofthe plural nodes operates as an antenna group of a cell. If nodes havedifferent cell IDs in the multi-node system, the multi-node system canbe regarded as a multi-cell (e.g., macro-cell/femto-cell/pico-cell)system. When multiple cells respectively configured by plural nodes areoverlaid according to coverage, a network configured by multiple cellsis called a multi-tier network. The cell ID of the RRH/RRU may beidentical to or different from the cell ID of an eNB. When the RRH/RRUand eNB use different cell IDs, both the RRH/RRU and eNB operate asindependent eNBs.

In a multi-node system according to the present invention, which will bedescribed below, one or more eNBs or eNB controllers connected to pluralnodes can control the plural nodes such that signals are simultaneouslytransmitted to or received from a UE through some or all nodes. Whilethere is a difference between multi-node systems according to the natureof each node and implementation form of each node, multi-node systemsare discriminated from single node systems (e.g. CAS, conventional MIMOsystems, conventional relay systems, conventional repeater systems,etc.) since a plurality of nodes provides communication services to a UEin a predetermined time-frequency resource. Accordingly, embodiments ofthe present invention with respect to a method of performing coordinateddata transmission using some or all nodes can be applied to varioustypes of multi-node systems. For example, a node refers to an antennagroup spaced apart from another node by a predetermined distance ormore, in general. However, embodiments of the present invention, whichwill be described below, can even be applied to a case in which a noderefers to an arbitrary antenna group irrespective of node interval. Inthe case of an eNB including an X-pole (cross polarized) antenna, forexample, the embodiments of the preset invention are applicable on theassumption that the eNB controls a node composed of an H-pole antennaand a V-pole antenna.

A communication scheme through which signals are transmitted/receivedvia plural transmit (Tx)/receive (Rx) nodes, signals aretransmitted/received via at least one node selected from plural Tx/Rxnodes, or a node transmitting a downlink signal is discriminated from anode transmitting an uplink signal is called multi-eNB MIMO or CoMP(Coordinated Multi-Point Tx/Rx). Coordinated transmission schemes fromamong CoMP communication schemes can be categorized into JP (JointProcessing) and scheduling coordination. The former may be divided intoJT (Joint Transmission)/JR (Joint Reception) and DPS (Dynamic PointSelection) and the latter may be divided into CS (CoordinatedScheduling) and CB (Coordinated Beamforming). DPS may be called DCS(Dynamic Cell Selection). When JP is performed, more variouscommunication environments can be generated, compared to other CoMPschemes. JT refers to a communication scheme by which plural nodestransmit the same stream to a UE and JR refers to a communication schemeby which plural nodes receive the same stream from the UE. The UE/eNBcombine signals received from the plural nodes to restore the stream. Inthe case of JT/JR, signal transmission reliability can be improvedaccording to transmit diversity since the same stream is transmittedfrom/to plural nodes. DPS refers to a communication scheme by which asignal is transmitted/received through a node selected from plural nodesaccording to a specific rule. In the case of DPS, signal transmissionreliability can be improved because a node having a good channel statebetween the node and a UE is selected as a communication node.

In the present invention, a cell refers to a specific geographical areain which one or more nodes provide communication services. Accordingly,communication with a specific cell may mean communication with an eNB ora node providing communication services to the specific cell. Adownlink/uplink signal of a specific cell refers to a downlink/uplinksignal from/to an eNB or a node providing communication services to thespecific cell. A cell providing uplink/downlink communication servicesto a UE is called a serving cell. Furthermore, channel status/quality ofa specific cell refers to channel status/quality of a channel or acommunication link generated between an eNB or a node providingcommunication services to the specific cell and a UE. In 3GPP LTE-Asystems, a UE can measure downlink channel state from a specific nodeusing one or more CSI-RSs (Channel State Information Reference Signals)transmitted through antenna port(s) of the specific node on a CSI-RSresource allocated to the specific node. In general, neighboring nodestransmit CSI-RS resources on orthogonal CSI-RS resources. When CSI-RSresources are orthogonal, this means that the CSI-RS resources havedifferent subframe configurations and/or CSI-RS sequences which specifysubframes to which CSI-RSs are allocated according to CSI-RS resourceconfigurations, subframe offsets and transmission periods, etc. whichspecify symbols and subcarriers carrying the CSI RSs.

In the present invention, PDCCH (Physical Downlink ControlChannel)/PCFICH (Physical Control Format Indicator Channel)/PHICH(Physical Hybrid automatic repeat request Indicator Channel)/PDSCH(Physical Downlink Shared Channel) refer to a set of time-frequencyresources or resource elements respectively carrying DCI (DownlinkControl Information)/CFI (Control Format Indicator)/downlink ACK/NACK(Acknowledgement/Negative ACK)/downlink data. In addition, PUCCH(Physical Uplink Control Channel)/PUSCH (Physical Uplink SharedChannel)/PRACH (Physical Random Access Channel) refer to sets oftime-frequency resources or resource elements respectively carrying UCI(Uplink Control Information)/uplink data/random access signals. In thepresent invention, a time-frequency resource or a resource element (RE),which is allocated to or belongs toPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH, is referred to as aPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE orPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource. In the followingdescription, transmission of PUCCH/PUSCH/PRACH by a UE is equivalent totransmission of uplink control information/uplink data/random accesssignal through or on PUCCH/PUSCH/PRACH. Furthermore, transmission ofPDCCH/PCFICH/PHICH/PDSCH by an eNB is equivalent to transmission ofdownlink data/control information through or onPDCCH/PCFICH/PHICH/PDSCH.

FIG. 1 illustrates an exemplary radio frame structure used in a wirelesscommunication system. FIG. 1(a) illustrates a frame structure forfrequency division duplex (FDD) used in 3GPP LTE/LTE-A and FIG. 1(b)illustrates a frame structure for time division duplex (TDD) used in3GPP LTE/LTE-A.

Referring to FIG. 1, a radio frame used in 3GPP LTE/LTE-A has a lengthof 10 ms (307200 Ts) and includes 10 subframes in equal size. The 10subframes in the radio frame may be numbered. Here, Ts denotes samplingtime and is represented as Ts=1/(2048*15 kHz). Each subframe has alength of 1 ms and includes two slots. 20 slots in the radio frame canbe sequentially numbered from 0 to 19. Each slot has a length of 0.5 ms.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources can be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame can be configured differently according to duplex mode.Downlink transmission is discriminated from uplink transmission byfrequency in FDD mode, and thus the radio frame includes only one of adownlink subframe and an uplink subframe in a specific frequency band.In TDD mode, downlink transmission is discriminated from uplinktransmission by time, and thus the radio frame includes both a downlinksubframe and an uplink subframe in a specific frequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink- DL-UL to-Uplink config- Switch-point Subframe numberuration periodicity 0 1 2 3 4 5 6 7 8 9 0  5 ms D S U U U D S U U U 1  5ms D S U U D D S U U D 2  5 ms D S U D D D S U D D 3 10 ms D S U U U D DD D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D D D D 6  5 ms DS U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes threefields of DwPTS (Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS(Uplink Pilot TimeSlot). DwPTS is a period reserved for downlinktransmission and UpPTS is a period reserved for uplink transmission.Table 2 shows special subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special Normal cyclic Extended Normal Extendedsubframe prefix in cyclic prefix cyclic prefix cyclic prefixconfiguration DwPTS uplink in uplink DwPTS in uplink in uplink 0  6592 ·T_(s) 2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s)1 19760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — —

FIG. 2 illustrates an exemplary downlink/uplink slot structure in awireless communication system. Particularly, FIG. 2 illustrates aresource grid structure in 3GPP LTE/LTE-A. A resource grid is presentper antenna port.

Referring to FIG. 2, a slot includes a plurality of OFDM (OrthogonalFrequency Division Multiplexing) symbols in the time domain and aplurality of resource blocks (RBs) in the frequency domain. An OFDMsymbol may refer to a symbol period. A signal transmitted in each slotmay be represented by a resource grid composed of N_(RB) ^(DL/UL)*N_(sc)^(RB) subcarriers and N_(symb) ^(DL/UL) OFDM symbols. Here, N_(RB) ^(DL)denotes the number of RBs in a downlink slot and N_(RB) ^(UL) denotesthe number of RBs in an uplink slot. N_(RB) ^(DL) and N_(RB) ^(UL)respectively depend on a DL transmission bandwidth and a UL transmissionbandwidth. N_(symb) ^(DL) denotes the number of OFDM symbols in thedownlink slot and N_(symb) ^(UL) denotes the number of OFDM symbols inthe uplink slot. In addition, N_(sc) ^(RB) denotes the number ofsubcarriers constructing one RB.

An OFDM symbol may be called an SC-FDM (Single Carrier FrequencyDivision Multiplexing) symbol according to multiple access scheme. Thenumber of OFDM symbols included in a slot may depend on a channelbandwidth and the length of a cyclic prefix (CP). For example, a slotincludes 7 OFDM symbols in the case of normal CP and 6 OFDM symbols inthe case of extended CP. While FIG. 2 illustrates a subframe in which aslot includes 7 OFDM symbols for convenience, embodiments of the presentinvention can be equally applied to subframes having different numbersof OFDM symbols. Referring to FIG. 2, each OFDM symbol includes N_(RB)^(DL/UL)*N_(sc) ^(RB) subcarriers in the frequency domain. Subcarriertypes can be classified into a data subcarrier for data transmission, areference signal subcarrier for reference signal transmission, and nullsubcarriers for a guard band and a direct current (DC) component. Thenull subcarrier for a DC component is a subcarrier remaining unused andis mapped to a carrier frequency (f0) during OFDM signal generation orfrequency up-conversion. The carrier frequency is also called a centerfrequency.

An RB is defined by N_(symb) ^(DL/UL) (e.g., 7) consecutive OFDM symbolsin the time domain and N_(sc) ^(RB) (e.g., 12) consecutive subcarriersin the frequency domain. For reference, a resource composed by an OFDMsymbol and a subcarrier is called a resource element (RE) or a tone.Accordingly, an RB is composed of N_(symb) ^(DL/UL)*N_(sc) ^(RB) REs.Each RE in a resource grid can be uniquely defined by an index pair (k,l) in a slot. Here, k is an index in the range of 0 to N_(symb)^(DL/UL)*N_(sc) ^(RB)−1 in the frequency domain and l is an index in therange of 0 to N_(symb) ^(DL/UL)−1.

Two RBs that occupy N_(sc) ^(RB) consecutive subcarriers in a subframeand respectively disposed in two slots of the subframe are called aphysical resource block (PRB) pair. Two RBs constituting a PRB pair havethe same PRB number (or PRB index). A virtual resource block (VRB) is alogical resource allocation unit for resource allocation. The VRB hasthe same size as that of the PRB. The VRB may be divided into alocalized VRB and a distributed VRB depending on a mapping scheme of VRBinto PRB. The localized VRBs are mapped into the PRBs, whereby VRBnumber (VRB index) corresponds to PRB number. That is, nPRB=nVRB isobtained. Numbers are given to the localized VRBs from 0 to N_(VRB)^(DL)−1, and N_(VRB) ^(DL)=N_(RB) ^(DL) is obtained. Accordingly,according to the localized mapping scheme, the VRBs having the same VRBnumber are mapped into the PRBs having the same PRB number at the firstslot and the second slot. On the other hand, the distributed VRBs aremapped into the PRBs through interleaving. Accordingly, the VRBs havingthe same VRB number may be mapped into the PRBs having different PRBnumbers at the first slot and the second slot. Two PRBs, which arerespectively located at two slots of the subframe and have the same VRBnumber, will be referred to as a pair of VRBs.

FIG. 3 illustrates a downlink (DL) subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 3, a DL subframe is divided into a control region anda data region. A maximum of three (four) OFDM symbols located in a frontportion of a first slot within a subframe correspond to the controlregion to which a control channel is allocated. A resource regionavailable for PDCCH transmission in the DL subframe is referred to as aPDCCH region hereinafter. The remaining OFDM symbols correspond to thedata region to which a physical downlink shared chancel (PDSCH) isallocated. A resource region available for PDSCH transmission in the DLsubframe is referred to as a PDSCH region hereinafter. Examples ofdownlink control channels used in 3GPP LTE include a physical controlformat indicator channel (PCFICH), a physical downlink control channel(PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc. ThePCFICH is transmitted at a first OFDM symbol of a subframe and carriesinformation regarding the number of OFDM symbols used for transmissionof control channels within the subframe. The PHICH is a response ofuplink transmission and carries an HARQ acknowledgment (ACK)/negativeacknowledgment (NACK) signal.

Control information carried on the PDCCH is called downlink controlinformation (DCI). The DCI contains resource allocation information andcontrol information for a UE or a UE group. For example, the DCIincludes a transport format and resource allocation information of adownlink shared channel (DL-SCH), a transport format and resourceallocation information of an uplink shared channel (UL-SCH), paginginformation of a paging channel (PCH), system information on the DL-SCH,information about resource allocation of an upper layer control messagesuch as a random access response transmitted on the PDSCH, a transmitcontrol command set with respect to individual UEs in a UE group, atransmit power control command, information on activation of a voiceover IP (VoIP), downlink assignment index (DAI), etc. The transportformat and resource allocation information of the DL-SCH are also calledDL scheduling information or a DL grant and the transport format andresource allocation information of the UL-SCH are also called ULscheduling information or a UL grant. The size and purpose of DCIcarried on a PDCCH depend on DCI format and the size thereof may bevaried according to coding rate. Various formats, for example, formats 0and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3 and 3Afor downlink, have been defined in 3GPP LTE. Control information such asa hopping flag, information on RB allocation, modulation coding scheme(MCS), redundancy version (RV), new data indicator (NDI), information ontransmit power control (TPC), cyclic shift demodulation reference signal(DMRS), UL index, channel quality information (CQI) request, DLassignment index, HARQ process number, transmitted precoding matrixindicator (TPMI), precoding matrix indicator (PMI), etc. is selected andcombined based on DCI format and transmitted to a UE as DCI.

In general, a DCI format for a UE depends on transmission mode (TM) setfor the UE. In other words, only a DCI format corresponding to aspecific TM can be used for a UE configured in the specific TM.

A PDCCH is transmitted on an aggregation of one or several consecutivecontrol channel elements (CCEs). The CCE is a logical allocation unitused to provide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). For example, a CCE corresponds to 9 REGs and an REG correspondsto 4 REs. 3GPP LTE defines a CCE set in which a PDCCH can be located foreach UE. A CCE set from which a UE can detect a PDCCH thereof is calleda PDCCH search space, simply, search space. An individual resourcethrough which the PDCCH can be transmitted within the search space iscalled a PDCCH candidate. A set of PDCCH candidates to be monitored bythe UE is defined as the search space. In 3GPP LTE/LTE-A, search spacesfor DCI formats may have different sizes and include a dedicated searchspace and a common search space. The dedicated search space is aUE-specific search space and is configured for each UE. The commonsearch space is configured for a plurality of UEs. Aggregation levelsdefining the search space is as follows.

TABLE 3 Search Space Aggregation Size Number of PDCCH Type Level L [inCCEs] candidates M^((L)) UE-specific 1 6 6 2 12 6 4 8 2 8 16 2 Common 416 4 8 16 2

A PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to CCEaggregation level. An eNB transmits a PDCCH (DCI) on an arbitrary PDCCHcandidate with in a search space and a UE monitors the search space todetect the PDCCH (DCI). Here, monitoring refers to attempting to decodeeach PDCCH in the corresponding search space according to all monitoredDCI formats. The UE can detect the PDCCH thereof by monitoring pluralPDCCHs. Since the UE does not know the position in which the PDCCHthereof is transmitted, the UE attempts to decode all PDCCHs of thecorresponding DCI format for each subframe until a PDCCH having the IDthereof is detected. This process is called blind detection (or blinddecoding (BD)).

The eNB can transmit data for a UE or a UE group through the dataregion. Data transmitted through the data region may be called userdata. For transmission of the user data, a physical downlink sharedchannel (PDSCH) may be allocated to the data region. A paging channel(PCH) and downlink-shared channel (DL-SCH) are transmitted through thePDSCH. The UE can read data transmitted through the PDSCH by decodingcontrol information transmitted through a PDCCH. Informationrepresenting a UE or a UE group to which data on the PDSCH istransmitted, how the UE or UE group receives and decodes the PDSCH data,etc. is included in the PDCCH and transmitted. For example, if aspecific PDCCH is CRC (cyclic redundancy check)-masked having radionetwork temporary identify (RNTI) of “A” and information about datatransmitted using a radio resource (e.g., frequency position) of “B” andtransmission format information (e.g., transport block size, modulationscheme, coding information, etc.) of “C” is transmitted through aspecific DL subframe, the UE monitors PDCCHs using RNTI information anda UE having the RNTI of “A” detects a PDCCH and receives a PDSCHindicated by “B” and “C” using information about the PDCCH.

A reference signal (RS) to be compared with a data signal is necessaryfor the UE to demodulate a signal received from the eNB. A referencesignal refers to a predetermined signal having a specific waveform,which is transmitted from the eNB to the UE or from the UE to the eNBand known to both the eNB and UE. The reference signal is also called apilot. Reference signals are categorized into a cell-specific RS sharedby all UEs in a cell and a modulation RS (DM RS) dedicated for aspecific UE. A DM RS transmitted by the eNB for demodulation of downlinkdata for a specific UE is called a UE-specific RS. Both or one of DM RSand CRS may be transmitted on downlink. When only the DM RS istransmitted without CRS, an RS for channel measurement needs to beadditionally provided because the DM RS transmitted using the sameprecoder as used for data can be used for demodulation only. Forexample, in 3GPP LTE(-A), CSI-RS corresponding to an additional RS formeasurement is transmitted to the UE such that the UE can measurechannel state information. CSI-RS is transmitted in each transmissionperiod corresponding to a plurality of subframes based on the fact thatchannel state variation with time is not large, unlike CRS transmittedper subframe.

FIG. 4 illustrates an exemplary uplink subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 4, a UL subframe can be divided into a control regionand a data region in the frequency domain. One or more PUCCHs (physicaluplink control channels) can be allocated to the control region to carryuplink control information (UCI). One or more PUSCHs (Physical uplinkshared channels) may be allocated to the data region of the UL subframeto carry user data.

In the UL subframe, subcarriers spaced apart from a DC subcarrier areused as the control region. In other words, subcarriers corresponding toboth ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a component remaining unused forsignal transmission and is mapped to the carrier frequency f0 duringfrequency up-conversion. A PUCCH for a UE is allocated to an RB pairbelonging to resources operating at a carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots.Assignment of the PUCCH in this manner is represented as frequencyhopping of an RB pair allocated to the PUCCH at a slot boundary. Whenfrequency hopping is not applied, the RB pair occupies the samesubcarrier.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response signal to a downlink data        packet on a PDSCH and indicates whether the downlink data packet        has been successfully received. A 1-bit ACK/NACK signal is        transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords. HARQ-ACK responses include positive ACK        (ACK), negative ACK (NACK), discontinuous transmission (DTX) and        NACK/DTX. Here, the term HARQ-ACK is used interchangeably with        the term HARQ ACK/NACK and ACK/NACK.    -   Channel State Indicator (CSI): This is feedback information        about a downlink channel. Feedback information regarding MIMO        includes a rank indicator (RI) and a precoding matrix indicator        (PMI).

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a soundingreference signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports various formats according toinformation transmitted thereon.

Table 4 shows the mapping relationship between PUCCH formats and UCI inLTE/LTE-A.

TABLE 4 Number of bits per PUCCH Modulation subframe, format schemeM_(bit) Usage Etc. 1  N/A N/A SR (Scheduling Request) 1a BPSK 1 ACK/NACKor One codeword SR + ACK/NACK 1b QPSK 2 ACK/NACK or Two codeword SR +ACK/NACK 2  QPSK 20 CQI/PMI/RI Joint coding ACK/NACK (extended CP) 2aQPSK + 21 CQI/PMI/RI + Normal CP BPSK ACK/NACK only 2b QPSK + 22CQI/PMI/RI + Normal CP QPSK ACK/NACK only 3  QPSK 48 ACK/NACK or SR +ACK/NACK or CQI/PMI/RI + ACK/NACK

Referring to Table 4, PUCCH formats 1/1a/1b are used to transmitACK/NACK information, PUCCH format 2/2a/2b are used to carry CSI such asCQI/PMI/RI and PUCCH format 3 is used to transmit ACK/NACK information.

In general, in order for a network obtain location information of a UEin a cellular communication system, various methods are used. In LTEsystem, a UE receives PRS (positioning reference signal) transmissionrelated information from a higher layer signal and measures PRSstransmitted by cells near the UE to deliver an RSTD (reference signaltime difference) corresponding to a difference between reception timingof a PRS transmitted by a reference eNB and reception timing of a PRStransmitted by a neighboring eNB to an eNB or a network. The networkcalculates a location of the UE by utilizing the RSTD and otherinformation. The abovementioned positioning scheme utilizes OTDOA(observed time difference of arrival). Besides, other schemes such asA-GNSS (Assisted Global Navigation Satellite System) positioning scheme,E-CID (Enhanced Cell-ID) scheme, UTDOA (Uplink Time Difference ofArrival), and the like exist. The positioning schemes can be utilizedfor various location-based services (e.g., advertisement, locationtracking, emergency communication means, etc.).

[LTE Positioning Protocol]

In LTE system, an LPP (LTE positioning protocol) has been defined tosupport the OTDOA scheme and the LPP informs a UE ofOTDOA-ProvideAssistanceData including configuration described in thefollowing as an IE (information element).

  -- ASN1START   OTDOA-ProvideAssistanceData ::= SEQUENCE {  otdoa-ReferenceCellInfo OTDOA-ReferenceCellInfo OPTIONAL,-- Need ON  otdoa-NeighbourCellInfo   OTDOA-NeighbourCellInfoList  OPTIONAL,--Need ON   otdoa-Error OTDOA-Error OPTIONAL, -- Need ON   ...   }   --ASN1STOP

In this case, the OTDOA-ReferenceCellInfo corresponds to a cell becominga reference for measuring RSTD. The OTDOA-ReferenceCellInfo isconfigured as follows.

 -- ASN1START  OTDOA-ReferenceCellInfo ::= SEQUENCE {  physCellIdINTEGER (0..503),  cellGlobalId ECGI OPTIONAL, -- Need ON  earfcnRefARFCN-ValueEUTRA   OPTIONAL, --   Cond NotSameAsServ0  antennaPortConfigENUMERATED {ports1-or-2, ports4, ... }  OPTIONAL,  -- CondNotSameAsServ1  cpLength ENUMERATED { normal, extended, ... },  prsInfoPRS-Info OPTIONAL, -- Cond PRS  ...,  [[ earfcnRef-v9a0ARFCN-ValueEUTRA-v9a0 OPTIONAL -- Cond NotSameAsServ2  ]]  }  --ASN1STOP

In this case, conditional presence is shown in the following.

TABLE 5 Conditional presence Description NotSameAsServ0 This field isabsent if earfcnRef-v9a0 is present. Otherwise, the field is mandatorypresent if the EARFCN of the OTDOA assistance data reference cell is notthe same as the EARFCN of the target devices's current primary cell.NotSameAsServ1 The field is mandatory present if the antenna portconfiguration of the OTDOA assistance data reference cell is not thesame as the antenna port configuration of the target devices's currentprimary cell. NotSameAsServ2 The field is absent if earfcnRef ispresent. Otherwise, the field is mandatory present if the EARFCN of theOTDOA assistance data reference cell is not the same as the EARFCN ofthe target devices's current primary cell. PRS The field is mandatorypresent if positioning reference signals are available in the assistancedata reference cell; otherwise it is not present.

Each field of the OTDOA-ReferenceCellInfo is described in the following.

TABLE 6 Description on OTDOA-ReferenceCellInfo fields physCellId Thisfield specifies the physical cell identity of the assistance datareference cell. cellGlobalId This field specifies the ECGI, the globallyunique identity of a cell in E-UTRA, of the assistance data referencecell. The server should include this field if it considers that it isneeded to resolve ambiguity in the cell indicated by physCellId.earfcnRef This field specifies the EARFCN of the assistance datareference cell. antennaPortConfig This field specifies whether 1 (or 2)antenna port(s) or 4 antenna ports for cell specific reference signals(CRS) are used in the assistance data reference cell. cpLength Thisfield specifies the cyclic prefix length of the assistance datareference cell PRS if the prsInfo field is present, otherwise this fieldspecifies the cyclic prefix length of the assistance data reference cellCRS. prsInfo This field specifies the PRS configuration of theassistance data reference cell.

Meanwhile, the OTDOA-NeighbourCellInfo corresponds to cells (e.g., eNBor TP) becoming a target of RSTD measurement. TheOTDOA-NeighbourCellInfo can include information on maximum 24 neighborcells according to a frequency layer for maximum 3 frequency layers. Inparticular, the OTDOA-NeighbourCellInfo can inform a UE of informationon 3*24=72 cells in total.

 -- ASN1START  OTDOA-NeighbourCellInfoList  ::=  SEQUENCE  (SIZE(1..maxFreqLayers)) OF OTDOA-NeighbourFreqInfo  OTDOA-NeighbourFreqInfo::= SEQUENCE (SIZE (1..24)) OF OTDOA-NeighbourCellInfoElement OTDOA-NeighbourCellInfoElement ::= SEQUENCE {  physCellId INTEGER(0..503),  cellGlobalId ECGI  OPTIONAL,  -- Need ON  earfcnARFCN-ValueEUTRA OPTIONAL, --    Cond NotSameAsRef0  cpLength ENUMERATED{normal, extended, ...}  OPTIONAL, -- Cond NotSameAsRef1  prsInfoPRS-Info OPTIONAL, -- Cond NotSameAsRef2  antennaPortConfig ENUMERATED{ports-1-or-2, ports-4, ...}  OPTIONAL, -- Cond NotsameAsRef3 slotNumberOffset INTEGER (0..19) OPTIONAL,-- Cond NotSameAsRef4 prs-SubframeOffset INTEGER (0..1279) OPTIONAL, --  Cond InterFreq expectedRSTD INTEGER (0..16383),  expectedRSTD-Uncertainty INTEGER(0..1023),  ...,  [[ earfcn-v9a0 ARFCN-Va1ueEUTRA-v9a0 OPTIONAL -- CondNotSameAsRef5  ]]  }  maxFreqLayers INTEGER ::= 3  -- ASN1STOP

In this case, conditional presence is shown in the following.

TABLE 7 Conditional presence Description NotSameAsRef0 The field isabsent if earfcn-v9a0 is present. If earfcn-v9a0 is not present, thefield is mandatory present if the EARFCN is not the same as for theassistance data reference cell; otherwise it is not present.NotSameAsRef1 The field is mandatory present if the cyclic prefix lengthis not the same as for the assistance data reference cell; otherwise itis not present. NotSameAsRef2 The field is mandatory present if the PRSconfiguration is not the same as for the assistance data reference cell;otherwise it is not present. NotSameAsRef3 The field is mandatorypresent if the antenna port configuration is not the same as for theassistance data reference cell; otherwise it is not present.NotSameAsRef4 The field is mandatory present if the slot timing is notthe same as for the assistance data reference cell; otherwise it is notpresent. NotSameAsRef5 The field is absent if earfcn is present. Ifearfcn is not present, the field is mandatory present if the EARFCN isnot the same as for the assistance data reference cell; otherwise it isnot present. InterFreq The field is optionally present, need OP, if theEARFCN is not the same as for the assistance data reference cell;otherwise it is not present.

Each field of the OTDOA-NeighbourCellInfoList is described in thefollowing.

TABLE 8 Description on OTDOA-NeighbourCellInfoList fields physCellIdThis field specifies the physical cell identity of the assistance datareference cell. cellGlobalId This field specifies the ECGI, the globallyunique identity of a cell in E-UTRA, of the assistance data referencecell. The server should include this field if it considers that it isneeded to resolve ambiguity in the cell indicated by physCellId.earfcnRef This field specifies the EARFCN of the assistance datareference cell. antennaPortConfig This field specifies whether 1 (or 2)antenna port(s) or 4 antenna ports for cell specific reference signals(CRS) are used in the assistance data reference cell. cpLength Thisfield specifies the cyclic prefix length of the neigbour cell PRS if PRSare present in this neighbour cell, otherwise this field specifies thecyclic prefix length of CRS in this neighbour cell. prsInfo This fieldspecifies the PRS configuration of the neighbour cell. When the EARFCNof the neighbour cell is the same as for the assistance data referencecell, the target device may assume that each PRS positioning occasion inthe neighbour cell at least partially overlaps with a PRS positioningoccasion in the assistance data reference cell where the maximum offsetbetween the transmitted PRS positioning occasions may be assumed to notexceed half a subframe. When the EARFCN of the neighbour cell is thesame as for the assistance data reference cell, the target device mayassume that this cell has the same PRS periodicity (Tprs) as theassistance data reference cell.

In this case, PRS-Info corresponding to IE included in theOTDOA-ReferenceCellInfo and the OTDOA-NeighbourCellInfo includes PRSinformation. Specifically, the PRS-Info including PRS Bandwidth, PRSConfiguration Index (IPRS), Number of Consecutive Downlink Subframes,and PRS Muting Information is configured as follows.

PRS-Info ::= SEQUENCE { prs-Bandwidth ENUMERATED { n6, n15, n25, n50,n75, n100, ... }, prs-ConfigurationIndex INTEGER (0..4095), numDL-FramesENUMERATED {sf-1, sf-2, sf-4, sf-6, ...}, ..., prs-MutingInfo-r9 CHOICE{ po2-r9 BIT STRING (SIZE(2)), po4-r9 BIT STRING (SIZE(4)), po8-r9 BITSTRING (SIZE(8)), po16-r9 BIT STRING (SIZE(16)), ... } OPTIONAL -- NeedOP } -- ASN1STOP

FIG. 5 is a diagram for a PRS transmission structure according to theaforementioned parameters.

In this case, PRS Periodicity and PRS Subframe Offset are determinedaccording to a value of PRS Configuration Index (IPRS) and acorresponding relation is shown in the following table.

TABLE 9 PRS Configuration Index PRS Periodicity PRS Subframe Offset(I_(PRS)) (subframes) (subframes)  0-159 160 I_(PRS) 160-479  320I_(PRS) − 160 480-1119 640 I_(PRS) − 480 1120-23399 1280  I_(PRS) − 1120

[PRS (Positioning Reference Signal)]

A PRS has a transmission occasion (i.e., a positioning occasion) with aperiod of 160, 320, 640, or 1280 ms and can be transmitted during Nnumber of continuous DL subframes at a positioning occasion. In thiscase, the N may have such a value as 1, 2, 4, or 6. Although it is ableto practically transmit a PRS at a positioning occasion, the PRS can bemuted at the positioning occasion for inter-cell interference controlcoordination. Information on the PRS muting is signaled to a UE usingprs-MutingInfo. Unlike a system bandwidth of a serving eNB, atransmission bandwidth of a PRS can be independently configured. A PRSis transmitted on a frequency band of 6, 15, 25, 50, 75, or 100 RBs(resource blocks). A transmission sequence of a PRS is generated byinitializing a pseudo-random sequence generator in every OFDM symbolusing functions of a slot index, an OFDM symbol index, a CP (cyclicprefix) type, and a cell ID. As shown in FIG. 6 (normal CP) and FIG. 7(extended CP), the generated transmission sequences of the PRS aremapped to a resource element (RE) depending on a CP type (normal CP andextended CP). A position of an RE to which a transmission sequence ismapped may shift on a frequency axis and a shift value is determined bya cell ID. FIGS. 6 and 7 show positions of PRS transmission REs wherefrequency shift corresponds to 0.

A UE receives configuration information on a list of PRSs to be searchedfrom a management server of a network to measure a PRS. Theconfiguration information includes PRS configuration information of areference cell and PRS configuration information of neighbor cells. Eachof the PRS configuration informations includes an occurrence interval ofa position occasion and offset, the number of continuous DL subframesconstructing a single positioning occasion, a cell ID used forgenerating a PRS sequence, a CP type, the number of CRS antenna portsconsidered for mapping a PRS, and the like. In addition, the PRSconfiguration information of the neighbor cells includes a slot offsetand a subframe offset between a neighbor cell and a reference cell,expected RSTD, and a level of uncertainty of the expected RSTD tosupport a UE to determine a time window for detecting a PRS transmittedby a neighbor cell.

Meanwhile, the RSTD corresponds to a relative timing difference betweenan adjacent or neighbor cell j and a reference cell i. In particular,the RSTD can be represented as T_(subframeRxj)−T_(subframeRxi). In thiscase, the T_(subframeRxj) corresponds to the timing at which a UEreceives the start of a specific subframe from the adjacent cell j andthe T_(subframeRxi) corresponds to the timing at which the UE receivesthe start of a subframe corresponding to the specific subframe from thereference cell i, which is closest to the specific subframe receivedfrom the adjacent cell j in time. A reference point for an examinedsubframe time difference corresponds to an antenna connector of the UE.

CRS-Related Signaling for RSTD Measurement

OTDOA positioning corresponds to a scheme of estimating a location of aUE estimated by a network, which has received an RSTD measurement reportfrom a PRS transmitted by each eNB. As mentioned in the foregoingdescription, RSTD corresponds to a difference between reception timing(e.g., time of arrival (TOA)) values measured from predeterminedsubframes of a reference cell and an adjacent cell. A UE converts theRSTD into a specific value of mapping table and reports the value to thenetwork.

According to the description on the OTDOA-ReferenceCellInfo field, ifprsInfo exists for a reference cell, the cpLength indicates CP lengthinformation of a reference cell PRS. Hence, the CP length information ofthe reference cell CRS does not exist. Similarly, according to thedescription on the OTDOA-NeighbourCellInfoElement field, if a PRS existsfor a specific neighbor cell, the cpLength indicates CP lengthinformation of a neighbor cell PRS. Hence, the CP length information ofthe neighbor cell CRS does not exist.

It may be able to perform RSTD measurement for OTDOA positioning byutilizing a PRS or utilizing both a PRS and a CRS depending onimplementation of a UE. If the RSTD measurement is performed byutilizing both the PRS and the CRS, since it is able to secure moreresources capable of being used for measurement compared to a case ofutilizing the PRS only, it may be able to increase accuracy.

Meanwhile, according to a current LTE standard, a CRS and a PRS may havea different type of CP in a specific subframe. For example, when apositioning occasion is configured in a subframe configured as an MBSFNsubframe, among OFDM symbols configured as an MBSFN region in the MBSFNsubframe, a CP of an OFDM symbol including a PRS may be configured as anextended CP, whereas a CP of an OFDM symbol including a CRS may beconfigured as a normal CP (a subframe #0 corresponds to a normal CP). Inparticular, although CP length information of a PRS for a specific cellis provided, because CP length information of a CRS for the cell is notprovided, ambiguity may occur. In particular, if information on a CPlength of a CRS is not clear, it may have a bad influence on RSTDmeasurement accuracy of a UE.

Similarly, if information on the number of CRS antenna ports of aspecific cell and information on an MBSFN subframe configuration are notclear, it may have a bad influence on accuracy of RSTD measurementmeasured by a UE based on a CRS of the cell. For example, if the numberof CRS antenna ports of a specific cell is precisely provided to a UE,the UE is able to accurately identify a resource to be used formeasuring RSTD. As a different example, if MBSFN subframeconfiguration-related information on a specific cell is preciselyprovided, it is able to identify whether or not the specific cellcorresponds to an MBSFN subframe in a specific subframe and identifythat a CRS is not transmitted in an MBSFN region of the subframe. Hence,it is able to accurately identify a resource to be used for measuringRSTD and perform RSTD measurement. The present invention proposes thefollowing.

A UE may receive or configured with all or a part of information on aspecific cell described in the following from a network (e.g., alocation server).

-   -   Information on the number of CRS antenna ports for a specific        cell    -   For example, the number of CRS antenna ports for a specific cell        may be explicitly provided to a UE using a value selected from        the group consisting of 1, 2, and 4. As mentioned in the        foregoing description, according to current LTE standard, it may        indicate one of two states including “1 or 2 antenna ports” and        “4 antenna ports”.    -   MBSFN subframe configuration information on a specific cell    -   For example, MBSFN subframe configuration information on a        specific cell may be explicitly provided to a UE in a unit of 1        or 4 radio frames.    -   CP length information of a CRS for a specific cell    -   For example, CP length information of a CRS for a specific cell        may be explicitly provided to a UE using either a normal CP        value or an extended CP value.    -   As a different example, there may exist a field for indicating        CP length information of a CRS only when a CP length of a CRS is        different from a CP length of a PRS for a specific cell. If the        field for indicating the CP length information of the CRS does        not exist, a UE considers that a CP length of a CRS and a CP        length of a PRS are identical to each other.

A UE may receive the abovementioned information from a location servervia an LPP (LTE positioning protocol) irrespective of informationprovided for cancelling CRS interference discussed earlier in feICIC(further enhanced inter-cell interference cancelation). The UE mayutilizes a CRS to measure RSTD without ambiguity for a specific cell CRSusing the aforementioned information.

If a UE fails to receive all or a part of “information on the number ofCRS antenna ports for a specific cell”, “MBSFN subframe configurationinformation on a specific cell”, and “CP length information of a CRS fora specific cell” from a network (e.g., a location server), it may definea rule for a UE behavior in order to make the UE not utilize a CRS forRSTD measurement.

Or, if a UE fails to receive all or a part of “information on the numberof CRS antenna ports for a specific cell”, “MBSFN subframe configurationinformation on a specific cell”, and “CP length information of a CRS fora specific cell” from a network (e.g., a location server), it may definea rule for a UE behavior in order to make the UE utilize a PRS only forRSTD measurement.

Or, when a UE fails to receive all or a part of “information on thenumber of CRS antenna ports for a specific cell”, “MBSFN subframeconfiguration information on a specific cell”, and “CP lengthinformation of a CRS for a specific cell” from a network (e.g., alocation server), if the UE uses a CRS to measure RSTD, it may define arule for a UE behavior in order to make the UE utilize an antenna port 0only.

Or, when a UE fails to receive all or a part of “information on thenumber of CRS antenna ports for a specific cell”, “MBSFN subframeconfiguration information on a specific cell”, and “CP lengthinformation of a CRS for a specific cell” from a network (e.g., alocation server), it may define a rule for a UE behavior in order tomake the UE utilize a CRS only among specific OFDM symbol(s) (e.g., allor a part of OFDM symbols of index=0, 1, 4, 7, 8, and 11) while a CRS isused for measuring RSTD.

It may define a rule of using a different RS to measure RSTD. Or, athird party RS may be newly defined and a UE may receive an RS-relatedconfiguration for a specific cell from a network (e.g., locationserver). For example, the RS-related configuration may be configured viaan LPP (LTE positioning protocol) or a specific higher layer signal.

According to LTE standard, a location server (e.g., E-SMLC) may provideassistant data for measuring RSTD to a UE to support OTDOA positioning.In this case, information on a reference cell and information on atarget cell (neighbor cell) are loaded on “OTDOA-ReferenceCellInfo” and“OTDOA-NeighbourCellInfoElement”, respectively. The UE performs PRStiming measurement using the information and reports a final RSTDmeasurement value to the location server. Yet, similar to CoMP scenario4, if the same physical cell ID is assigned to a plurality of TPs/RRHs(remote radio heads) belonging to a specific cell, since a PRS/CRS istransmitted in a manner that a single physical cell ID corresponding toa plurality of the TPs/RRHs is generated and the cell ID is mapped tothe same RE, the UE is unable to identify a TP/RRH from which thePRS/CRS is transmitted.

Hence, when assistant data for measuring RSTD is set to the UE, if“physCellId” field belonging to the assistant data for two specificcells indicates the same value, a behavior of the UE may be defined asfollows.

-   -   If “OTDOA-ReferenceCellInfo” and “physCellId” field belonging to        “OTDOA-NeighbourCellInfoElement” for a specific cell (one or a        plurality of cells) indicate the same value,    -   it may predefine a rule that the UE measures a PRS only        corresponding to a reference cell and measurement on a neighbor        cell(s) is not performed. In this case, the UE does not report        RSTD measurement measured on the neighbor cell(s).    -   it may predefine a rule that the UE measures a PRS only        corresponding to a reference cell and PRS measurement is        performed on a neighbor cell(s) only or CRS measurement is not        performed on the neighboring cell(s).    -   it may predefine a rule that the UE measures a PRS corresponding        to a reference cell and/or a CRS and measurement is not        performed on a neighbor cell(s). In this case, the UE does not        report RSTD measurement measured on the neighbor cell(s).    -   it may predefine a rule that the UE measures a PRS corresponding        to a reference cell and/or a CRS and PRS measurement is        performed on a neighbor cell(s) only or CRS measurement is not        performed on the neighboring cell(s).    -   If “physCellId” field belonging to        “OTDOA-NeighbourCellInfoElement” for a plurality of specific        cells indicates the same value,    -   it may predefine a rule that the UE performs PRS measurement on        a first (or a predefined/predetermined) cell belonging to        “OTDOA-NeighbourFreqInfo” only and measurement on the remaining        cells is not performed. In this case, the UE does not report        RSTD measurement measured on the remaining cells.    -   it may predefine a rule that the UE performs PRS measurement on        a first (or a predefined/predetermined) cell belonging to        “OTDOA-NeighbourFreqInfo” only and PRS measurement is performed        on the remaining cells only or CRS measurement is not performed        on the remaining cells.    -   it may predefine a rule that the UE performs PRS measurement        and/or CRS measurement on a first (or a        predefined/predetermined) cell belonging to        “OTDOA-NeighbourFreqInfo” only and measurement on the remaining        cells is not performed. In this case, the UE does not report        RSTD measurement measured on the remaining cells.    -   it may predefine a rule that the UE performs PRS measurement        and/or CRS measurement on a first (or a        predefined/predetermined) cell belonging to        “OTDOA-NeighbourFreqInfo” and PRS measurement is performed on        the remaining cells only or CRS measurement is not performed on        the remaining cells.

It may predefine a rule that the abovementioned rules are applied when“OTDOA-NeighbourCellInfoElement” for a plurality of cells is included inthe same OTDOA-NeighbourFreqInfo only (or, irrespective of theOTDOA-NeighbourFreqInfo).

In order to more accurately estimate a channel property of a PRS signaltransmitted from an eNB or a TP, it may be able to additionally notifyinformation on an RS including reception property identical to receptionproperty of the PRS. The information may be referred to as QCL(quasi-co-location) information of channel property. It may be able tofinally determine the channel property of the PRS by utilizing a channelproperty of a signal in a QCL relation and a measurement value for thechannel property of the PRS at the same time.

If a UE fails to receive “QCL information between a PRS for a specificcell and a specific RS” from a network (e.g., a location server), it maybe able to define a rule for a UE behavior that the UE utilizes a PRSonly to measure RSTD or the UE does not use the specific RS (e.g., CRS,CSI-RS, etc.).

The “QCL information between a PRS for a specific cell and a specificRS” may indicate that the PRS and a (predefined/predetermined) specificantenna port of the specific RS is in QCL relation only. Having receivedthe information from the network, the UE may use the specific antennaport only of the RS to measure RSTD.

Since it is able to include the examples for the proposed method as oneof implementation methods of the present invention, it is apparent thatthe examples are considered as a sort of proposed methods. Although theembodiments of the present invention may be independently implemented,the embodiments may also be implemented in a combined/aggregated form ofa part of embodiments. It may define a rule that an eNB/location serverinforms a UE of information on whether to apply the proposed methods(or, information on rules of the proposed methods) via a predefinedsignal (e.g., physical layer signal or higher layer signal).

FIG. 8 is a diagram illustrating an operation according to oneembodiment of the present invention.

FIG. 8 shows an operation of measuring a reference signal fordetermining a location in a wireless communication system. The operationis performed by a terminal 81.

The terminal may receive assistant data related to a reference cell andone or more neighbor cells for positioning [S810]. The terminal mayreceive a positioning reference signal (PRS) or a cell-specificreference signal (CRS) of the reference cell and the one or moreneighbor cells and calculate a reference signal time difference (RSTD)measurement value [S820]. The terminal may report the measurement valueto a location server [S830].

The assistant data may include information on the number of CRS antennaports, CRS cyclic prefix (CP) length information, or configurationinformation on multicast broadcast single frequency network (MBSFN)subframes of the reference cell and the one or more neighbor cells.

And, the information on the number of CRS antenna ports may indicate oneselected from the group consisting of 1, 2 and 4.

And, the CRS CP length information may exist only when the PRS of thereference cell is different from a CP length of the CRS of the referencecell or when the PRS of the one or more neighbor cells is different fromthe CP length of the CRS of the one or more neighbor cells. when the CRSCP length information is not included in the assistant data, the PRS ofthe reference cell is identical to the CP length of the CRS of thereference cell or the PRS of the one or more neighbor cells is identicalto the CP length of the CRS of the one or more neighbor cells.

And, the configuration information on the MBSFN subframes may beprovided in a unit of 1 or 4 radio frames.

When the assistant data related to a specific cell of the one or moreneighbor cells does not include all or a part of the information on thenumber of CRS antenna ports, the CRS CP length information, and theconfiguration information on the MBSFN subframes, a CRS may be used forthe RSTD measurement for the specific cell.

When the assistant data related to a specific cell of the one or moreneighbor cells does not include all or a part of the information on thenumber of CRS antenna ports, the CRS CP length information, and theconfiguration information on the MBSFN subframes, the terminal maycalculate the RSTD measurement value by receiving a CRS only transmittedvia a CRS port 0 of the specific cell.

When the assistant data related to a specific cell of the one or moreneighbor cells does not include all or a part of the information on thenumber of CRS antenna ports, the CRS CP length information, and theconfiguration information on the MBSFN subframes, the terminal maycalculate the RSTD measurement value by receiving a CRS transmitted viaa specific OFDM symbol only, which transmitted from the specific cell.

When the assistant data related to a specific cell of the one or moreneighbor cells does not include all or a part of the information on thenumber of CRS antenna ports, the CRS CP length information, and theconfiguration information on the MBSFN subframes, the terminal maycalculate the RSTD measurement value by receiving a PRS only, whichtransmitted from the specific cell.

When a physical layer cell identifier (ID) field of the reference cellis identical to a physical cell ID of at least one neighbor cell amongthe one or more neighbor cells, only a PRS of the reference cell may beused for measuring RSTD and RSTD measurement may be not performed forthe at least one neighbor cell.

When a physical layer cell identifier (ID) field of the reference cellis identical to a physical cell ID of at least one neighbor cell amongthe one or more neighbor cells, only a PRS of the reference cell may beused for measuring RSTD and only a PRS of the at least one neighbor cellmay be used for measuring RSTD.

When a physical layer cell identifier (ID) field of the reference cellis identical to a physical cell ID of at least one neighbor cell amongthe one or more neighbor cells, a PRS and/or a CRS of the reference cellmay used for measuring RSTD and RSTD measurement may not be performedfor the at least one neighbor cell.

When a physical layer cell identifier (ID) field of the reference cellis identical to a physical cell ID of at least one neighbor cell amongthe one or more neighbor cells, a PRS and/or a CRS of the reference cellmay be used for measuring RSTD and only a PRS of the at least oneneighbor cell may be used for measuring RSTD.

When physical layer cell identifiers (IDs) of a plurality of neighborcells included in the assistant data are identical to each other, only aPRS of a predetermined neighbor cell among a plurality of the neighborcells may used for measuring RSTD and RSTD measurement may not beperformed for the remaining neighbor cells other than the predeterminedneighbor cell.

If physical layer cell identifiers (IDs) of a plurality of neighborcells included in the assistant data are identical to each other, only aPRS of a predetermined neighbor cell among a plurality of the neighborcells is used for measuring RSTD and only PRS of the remaining neighborcells other than the predetermined neighbor cell may be used formeasuring RSTD.

If physical layer cell identifiers (IDs) of a plurality of neighborcells included in the assistant data are identical to each other, a PRSand/or a CRS of a predetermined neighbor cell among the plurality of theneighbor cells may be used for measuring RSTD and RSTD measurement maynot be performed for the remaining neighbor cells other than thepredetermined neighbor cell.

If physical layer cell identifiers (IDs) of a plurality of neighborcells included in the assistant data are identical to each other, a PRSand/or a CRS of a predetermined neighbor cell among the plurality of theneighbor cells is used for measuring RSTD and only PRS of the remainingneighbor cells other than the predetermined neighbor cell may be usedfor measuring RSTD.

The terminal may receive information on a specific reference signal(RS), which is in a quasi-co-location (QCL) relation with a PRS of thereference cell or the one or more neighbor cells. The information on thespecific RS may be used for determining a channel property of the PRS,which is in the QCL relation with the RS.

The information on the specific RS may include information on a specificantenna port of the RS, which is in the QCL relation with the PRS.

In the foregoing description, embodiments of the present invention havebeen briefly explained with reference to FIG. 8. An embodiment relatedto FIG. 8 can alternatively or additionally include at least a part ofthe aforementioned embodiments.

FIG. 9 is a block diagram illustrating a transmitting device 10 and areceiving device 20 configured to implement embodiments of the presentinvention. Each of the transmitting device 10 and receiving device 20includes transmitter/receiver 13, 23 capable of transmitting orreceiving a radio signal that carries information and/or data, a signal,a message, etc., a memory 12, 22 configured to store various kinds ofinformation related to communication with a wireless communicationsystem, and a processor 11, 21 operatively connected to elements such asthe transmitter/receiver 13, 23 and the memory 12, 22 to control thememory 12, 22 and/or the transmitter/receiver 13, 23 to allow the deviceto implement at least one of the embodiments of the present inventiondescribed above.

The memory 12, 22 may store a program for processing and controlling theprocessor 11, 21, and temporarily store input/output information. Thememory 12, 22 may also be utilized as a buffer. The processor 11, 21controls overall operations of various modules in the transmitter or thereceiver. Particularly, the processor 11, 21 may perform various controlfunctions for implementation of the present invention. The processors 11and 21 may be referred to as controllers, microcontrollers,microprocessors, microcomputers, or the like. The processors 11 and 21may be achieved by hardware, firmware, software, or a combinationthereof. In a hardware configuration for an embodiment of the presentinvention, the processor 11, 21 may be provided with applicationspecific integrated circuits (ASICs) or digital signal processors(DSPs), digital signal processing devices (DSPDs), programmable logicdevices (PLDs), and field programmable gate arrays (FPGAs) that areconfigured to implement the present invention. In the case which thepresent invention is implemented using firmware or software, thefirmware or software may be provided with a module, a procedure, afunction, or the like which performs the functions or operations of thepresent invention. The firmware or software configured to implement thepresent invention may be provided in the processor 11, 21 or stored inthe memory 12, 22 to be driven by the processor 11, 21.

The processor 11 of the transmitting device 10 performs predeterminedcoding and modulation of a signal and/or data scheduled by the processor11 or a scheduler connected to the processor 11, and then transmits asignal and/or data to the transmitter/receiver 13. For example, theprocessor 11 converts a data sequence to be transmitted into K layersthrough demultiplexing and channel coding, scrambling, and modulation.The coded data sequence is referred to as a codeword, and is equivalentto a transport block which is a data block provided by the MAC layer.One transport block is coded as one codeword, and each codeword istransmitted to the receiver in the form of one or more layers. Toperform frequency-up transformation, the transmitter/receiver 13 mayinclude an oscillator. The transmitter/receiver 13 may include Nttransmit antennas (wherein Nt is a positive integer greater than orequal to 1).

The signal processing procedure in the receiving device 20 is configuredas a reverse procedure of the signal processing procedure in thetransmitting device 10. The transmitter/receiver 23 of the receivingdevice 20 receives a radio signal transmitted from the transmittingdevice 10 under control of the processor 21. The transmitter/receiver 23may include Nr receive antennas, and retrieves baseband signals byfrequency down-converting the signals received through the receiveantennas. The transmitter/receiver 23 may include an oscillator toperform frequency down-converting. The processor 21 may perform decodingand demodulation on the radio signal received through the receiveantennas, thereby retrieving data that the transmitting device 10 hasoriginally intended to transmit.

The transmitter/receiver 13, 23 includes one or more antennas. Accordingto an embodiment of the present invention, the antennas function totransmit signals processed by the transmitter/receiver 13, 23 are toreceive radio signals and deliver the same to the transmitter/receiver13, 23. The antennas are also called antenna ports. Each antenna maycorrespond to one physical antenna or be configured by a combination oftwo or more physical antenna elements. A signal transmitted through eachantenna cannot be decomposed by the receiving device 20 anymore. Areference signal (RS) transmitted in accordance with a correspondingantenna defines an antenna from the perspective of the receiving device20, enables the receiving device 20 to perform channel estimation on theantenna irrespective of whether the channel is a single radio channelfrom one physical antenna or a composite channel from a plurality ofphysical antenna elements including the antenna. That is, an antenna isdefined such that a channel for delivering a symbol on the antenna isderived from a channel for delivering another symbol on the sameantenna. An transmitter/receiver supporting the Multiple-InputMultiple-Output (MIMO) for transmitting and receiving data using aplurality of antennas may be connected to two or more antennas.

In embodiments of the present invention, the UE operates as thetransmitting device 10 on uplink, and operates as the receiving device20 on downlink. In embodiments of the present invention, the eNBoperates as the receiving device 20 on uplink, and operates as thetransmitting device 10 on downlink.

The transmitter and/or receiver may be implemented by one or moreembodiments of the present invention among the embodiments describedabove.

Detailed descriptions of preferred embodiments of the present inventionhave been given to allow those skilled in the art to implement andpractice the present invention. Although descriptions have been given ofthe preferred embodiments of the present invention, it will be apparentto those skilled in the art that various modifications and variationscan be made in the present invention defined in the appended claims.Thus, the present invention is not intended to be limited to theembodiments described herein, but is intended to have the widest scopeconsistent with the principles and novel features disclosed herein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wireless communication devicessuch as a terminal, a relay, and a base station.

1-20. (canceled)
 21. A method of measuring a reference signal for positioning in a wireless communication system, the method performed by a terminal and comprising: receiving assistant data related to a reference cell and one or more neighbor cells for positioning; calculating a reference signal time difference (RSTD) measurement value using a positioning reference signal (PRS) and a cell-specific reference signal (CRS) of the reference cell and the one or more neighbor cells based on the assistant data; and reporting the measurement value to a location server, wherein the assistant data includes at least one of CRS cyclic prefix (CP) length information of the reference cell and the one or more neighbor cells and multicast broadcast single frequency network (MBSFN) subframes configuration information of the reference cell and the one or more neighbor cells.
 22. The method of claim 21, wherein the assistant data further includes the information on the number of CRS antenna ports indicates one selected from the group consisting of 1, 2, and
 4. 23. The method of claim 21, wherein the CRS CP length information exists only when a CP length of a PRS of the reference cell is different from a CP length of a CRS of the reference cell or a CP length of a PRS of the one or more neighbor cells is different from a CP length of a CRS of the one or more neighbor cells.
 24. The method of claim 23, wherein if the CRS CP length information is not included in the assistant data, the CP length of the PRS of the reference cell is identical to the CP length of the CRS of the reference cell or the CP length of the PRS of the one or more neighbor cells is identical to the CP length of the CRS of the one or more neighbor cells.
 25. The method of claim 21, wherein the configuration information on the MBSFN subframes is provided in a unit of 1 or 4 radio frames.
 26. The method of claim 22, wherein when the assistant data related to a specific cell of the reference cell and the one or more neighbor cells does not include all or a part of the information on the number of CRS antenna ports, the CRS CP length information, and the MBSFN subframes configuration information, a CRS is not used for the RSTD measurement for the specific cell.
 27. The method of claim 22, wherein when the assistant data related to a specific cell of the reference cell and the one or more neighbor cells does not include all or a part of the information on the number of CRS antenna ports, the CRS CP length information, and the MBSFN subframes configuration information, the method further comprises calculating the RSTD measurement value by receiving a CRS only transmitted via a CRS port 0 of the specific cell, by receiving a CRS on a specific OFDM symbol only, which transmitted from the specific cell, or by receiving a PRS only, which transmitted from the specific cell.
 28. The method of claim 21, wherein when a physical layer cell identifier (ID) field of the reference cell is identical to a physical cell ID of at least one neighbor cell among the one or more neighbor cells, a PRS and/or a CRS of the reference cell is used for measuring RSTD and RSTD measurement is not performed for the at least one neighbor cell.
 29. The method of claim 21, wherein when a physical layer cell identifier (ID) field of the reference cell is identical to a physical cell ID of at least one neighbor cell among the one or more neighbor cells, a PRS and/or a CRS of the reference cell is used for measuring RSTD and only a PRS of the at least one neighbor cell is used for measuring RSTD.
 30. The method of claim 21, wherein when physical layer cell identifiers (IDs) of a plurality of neighbor cells included in the assistant data are identical to each other, a PRS and/or a CRS of a predetermined neighbor cell among the plurality of the neighbor cells is used for measuring RSTD and RSTD measurement is not performed for the remaining neighbor cells other than the predetermined neighbor cell.
 31. The method of claim 21, wherein when physical layer cell identifiers (IDs) of a plurality of neighbor cells included in the assistant data are identical to each other, a PRS and/or a CRS of a predetermined neighbor cell among the plurality of the neighbor cells is used for measuring RSTD and only PRS of the remaining neighbor cells other than the predetermined neighbor cell are used for measuring RSTD.
 32. The method of claim 21, further comprising receiving information on a specific reference signal (RS), which is in a quasi-co-location (QCL) relation with the PRS of the reference cell or the one or more neighbor cells, wherein the information on the specific RS is used for determining a channel property of the PRS, which is in the QCL relation with the RS.
 33. The method of claim 32, wherein the information on the specific RS includes information on a specific antenna port of the RS, which is in the QCL relation with the PRS.
 34. A terminal for measuring a reference signal for positioning in a wireless communication system, the terminal comprising: a transmitter; a receiver; and a processor that controls the transmitter and the receiver, wherein the processor controls the receiver to receive assistant data related to a reference cell and one or more neighbor cells for positioning, calculates a reference signal time difference (RSTD) measurement value using a positioning reference signal (PRS) and a cell-specific reference signal (CRS) of the reference cell and the one or more neighbor cells based on the assistant data, and reports the measurement value to a location server, and wherein the assistant data includes at least one of CRS cyclic prefix (CP) length information of the reference cell and the one or more neighbor cells and multicast broadcast single frequency network (MBSFN) subframes configuration information of the reference cell and the one or more neighbor cells. 